Clojurians Log v2

You said that nil isn't added to the output collection but this seems to contradict it:

(for [x [1 2 nil 3]] 
  x)
;;=> (1 2 nil 3)

Huh, that is true, looks like you have to add a :when to skip the nils:

(for [x [1 2 nil 3] :when x] 
  x)
;;=> (1 2 3)

good catch